As a preventative maintenance task, I replaced both the ICE belt driven water pump and the inverter pump and in the process drained what I could of all the coolant in both of those closed systems. Now that I have everything put back together, I followed what I thought was good advice from a few videos that I saw on youtube for adding coolant and bleeding the systems. At this point I have dumped probably 1/2 gallon total into those systems. the inverter reservior is full. I have a neat radiator filler tool that locks onto the radiator (its like a funnel that won't leak) and that's overfilled waiting for fluid to be drawn in. The simplest seemed to be the inverter coolant I filled that to the top and with a hose from the bleeder back to the inverter filler cap. I touch the power button twice to put the prius in "accessory" mode ( not running ) and the new electric pump started to whir into action. The open bleeder didn't seem to be doing much of anything and the coolant in the fill tank remains full. videos showed coolant surging through the bleeder tube back to the tank when the pump was running. I gave up on that for now. I turned to the engine coolant loop and followed the instructions to open the bleeder on top of the radiator. It allowed some coolant out and then leaked through the allen bolt that closes that valve. I energized the pump that cycles coolant into the thermal tank and the overfilled radiator filler level didn't go down. I even started the ICE and that level did not go down. What the hell. I shut everything off and walked away. It would be pretty ironic if I destroy a new part because it ran dry when all I was trying to do was some "simple" maintenance. All parts (including fluid) are Toyota OEM from a local dealer. Any suggestions? The car was running fine prior to this as far as I could tell and I did this very same operation on another Prius several years ago without any complications from what I can remember. Some things I checked. Accessory drive belt is on and is tight. All electrical conections for thermal tank and pump are connected The inverter coolant bleeder didn't have a rubber cover, but I took off the valve and its clean and air can pass through.
You're in a Gen too just like mine these are generally no issue to do this no let it get to you just fill everything up leave the caps off and leave it sitting just a couple hours If you want to start it and do whatever you're not hurting anything it's just going to go down if it needs to you know what you've put in I doubt you're going to destroy anything in your gen too you put new coolant parts in Great they're not running dry believe me the air will work its way up
I may save the bleed procedure for when I get the car completely assembled. Doing other suspension and front end work and don't want to run it for a long time in the garage on jackstands. Thanks for the info and encouragement. I did find a lot of air in the tube from the pump to the reservoir.
Try squeezing and rubber tube on the coolant system. Pouring air this way might encourage the air locked system to burp itself.
I did try squeezing any with mixed results. Gotta love this Prius. I moved the car on the 7 seconds of electric power after startup out of the garage so I could try to get it in maintenance mode. In that short period of time it gulped down all the fluid in the inverter reservior and I was able to add a significant amount more. No idea why all my other attempts at this didn't do anything. I am still having issues with the engine coolant. PITA.
After a brief drive with the heat on and no warm air, I let the car sit until things cooled down. I was able to add more coolant to the radiator. Seems like this may be successful if I cycle over a few times. That is what the official docs indicated was the way to burp the engine cooling loop. May even go back and retry the thermal canister purge, although that may also happen over time...
For future lurkers dont ever do a full coolant loop change. Its very difficult to bleed and you may end up with a air locked bubble in the cylinder head. Even many a dealer cannot get this right. Over heated aluminum head and you will never know as the car has no temp gauge. No heat is a real good hint you have an air locked head. Driving it and hoping it self bleeds itself without temp monitoring is foolish. very easy to damage the little aluminum head. Seen many on this site. If a coolant change is necessary like with a water pump replacement I would use a scan gauge that monitors engine temp till you have good heat and a quiet heat exchanger under the dash. No gurgling. Basic coolant maintenance can be achieved by just dumping the rad only. Fill it back up drive away no air lock drama. Do that a few times and your good.
Wouldn't draining the radiator also drain a lot of fluid from anything connected to the radiator? This is my experience, with 3rd gen, so not sure how much if any it applies, but the drain instruction in Repair Manual is to drain the radiator (open the spigot at the bottom), and the block (unscrew the bleed bolt on back of block). When I did that second step (likely for the last time) I got at most a quarter cup of coolant. And it was just nuts getting to it. Also, when doing EGR cleaning, I purposely drained 2 liters (from the radiator spigot), and that was enough to drop the level below all the EGR components, and the engine coolant reservoir just had an inch or so at the bottom. In a nutshell, third gen drain and fill IS basically a radiator drain. I appreciate gen 2 is different, has that thermos for example. Might be completely off-the-mark, lol.
Mendel. What you sent was the shop manual for a gen2. They used a tool to bleed the thermos. That can also be done by energizing at a relay. The engine coolant routine is what I was doing... BUT. I see the point that edthefox5 is making. you can't just fill and go... or take a long trip on the highway with trapped air pockets in the engine. I will take the good advice he gave and hook up my torque app and monitor whatever temps it provides and probably take another quick trip around the neighborhood. Glad I didn't push it. On another note, I only drove a little in my neighborhood because I couldn't get the car in maintenance mode. I followed directions I saw for the key in slot, press power twice, press gas pedal 2x, foot on brake shift to N, gas 2X, foot on brake shift to P, gas 2x, foot on brake and power to start. No joy. maybe its not registering a full gas pedal press?
One thing I missed in the youtube videos for this coolant replacement is everyone was jacking the car up on the passenger side. I also have a sloppy radiator bleed valve, it leaks around the valve screw and makes a mess even though I connected plastic tubing. So this latest go around I got the thermal pump to sound better either by the passing of time or this time I left the radiator bleeder open. I had the car jacked up and bleeder open. Started the car in mainenance mode. Had a good quart of fluid in a funnel above the radiator. I watched the coolant temp readings and it rose steadily to 180 and the upper radiator hose by the radiator bleed valve got warm. At around 200+ the fan came on. No coolant was drawn into the system and I think I am still about 1-2 quarts low. I turned on the climate control to hot when the engine had reached operating temp and it still blew cold air. Is it a mistake to button things up and fill the overflow, go on a few short drives and watch the coolant temp and monitor for interior heat, bubbling noises and fluid levels after each trip at this point? Using the youtube bleed procedure in maintenance mode is giving me no joy at all.
I see the point that edthefox5 is making. you can't just fill and go... or take a long trip on the highway with trapped air pockets in the engine. Exactly! this also happens in the second Gen Range Rover. Air locked coolant system and an aluminum engine equal cracked blocks and totaled Rovers. Since these truck are worth about $1,800.00 most people just junk them.
I think I understand the danger, but now trying to come up with a way forward. Luckily this isn't a vehicle I need to put into use right away, but I would like to finish this job.
you need the coolant funnel to remove air from the system and there a screw on the radiator to let out too if i remember right and you have to put the prius into maintenance mode to keep the engine running.
Still no success with this.. coolant temps 170-200, short drive (few miles, back streets), no interior heat or even bubbling sounds, still at least a quart low, nothing being drawn from overflow tank Some more specific questions. Is the coolant temp my only way to monitor engine temperatures? Is there anything that can restrict coolant from the heater core? The electric pump? Is that pump out of the loop when the engine is running?
Good questions! The Gen 1 electric heater pump was a bit restrictive, and had a bypass valve to take it out of the loop when the engine was running. Gen 2 changed that pump to a less restrictive one, and did away with the bypass valve. But Gen 2 does have a "coolant control valve", which changes the coolant routing for storing/returning hot coolant in/from the Gen 2 thermos, and in certain positions that will restrict heater core flow. That valve (or really its position sensor) is also a known trouble item at higher miles. Have you checked its operation, or seen any of its related trouble codes?
No CEL on this car. Probably doesn't help that it hasn't really gone through many (if any) drive cycles since I replaced these parts. There were no codes prior to the work. I wish I knew if there was heat in this car prior to the work. I bought in January last year... worked on it for a while. Only had it on the road briefly during some warmer weather. Since you didn't object to the coolant temp part of the question, I am going to assume that monitoring engine temp with the coolant temp is my only option and 185-200 is a pretty good target for a normal temp. Not sure what thermostat is in the car, or even what the stock temp is for that to open.
Sounds like about the right range. The thermostat details are in the repair manual if you want to dive deeper. I think there is another temperature sensor at the outlet of the thermos. You can compare that to the reading from the cylinder head. Of course it may be different, depending on what the coolant control valve and thermos pump are doing.
Most in your case have had success by jacking the cars front up high put the car in maintenance mode let the engine idle non stop and leave the rad cap off till all the bubbles reach the rad height and bubble out. Maybe squeeze the hoses now and then too. make sure heat is off. You can see if its helping as the coolant level at the rad neck will continuously get lower as the bubbles vacate. Just keep topping off. Make sure you use Toyota LLC coolant. All the while keeping an eye on the engine temp. NJ is probably getting cold so may take quite a while to warm up. May have to close the hood. Cover the rad front with a blanket or piece of cardboard. Lots of people run the cardboard all winter. Got to get engine warm to open the thermostat. It opens at 180 F. Don't feel bad this is a real pain in the neck coolant loop with the CHRS tank. Good luck.
Well... the coolant situation finally seems stable. What really seemed to help was putting the car up on jackstands to lift the front and letting it run in maintenance mode for a while. Bubbles did not appear in the funnel until the car had reached operating temp... and then it still took some time, but slowly it started to bubble and draw in liquid. I tried to help by pressing radiator hoses until they were almost too warm to touch. The coolant temp never got over 205 when the fans kicked in. Thermostat seemed to open around 180-190, so working as expected. Finally after running about 30 minutes the bubbles stopped, so I shut it down. Prior to turning it off, I tried the cabin heat and it was cold... Wth? I gave up and assumed a different problem. Today I did a test drive and cabin heat was there... maybe that electric pump that circulates through the heater core is not activated in maintenance mode. Not sure. Summary. Measure what you take out. (Probably best to make sure radiator is filled prior to draining) Target getting back in the same amount or a little more (spillage) Fill as much as you can Use the trick to prime the coolant tank (might help to keep the radiator valve open for this...) Walk away when things don't work (LOL) When you get a good prime on the tank. Run in maintenance mode and be patient. May take 30 minutes or more to get that air out. Slow process. Don't turn on cabin heat during the maintenance mode step.
